I want you to be aware of some related cross-platform summary information that is also available.
A developerWorks article with the title "Selected common SQL features for developers of portable DB2 applications" provides a set of tables that provides a summary of the common SQL application features and is intended to be a quick reference that includes the frequently used features and functions across the DB2 platforms. the features are broken out into 19 tables that are categorized (with quick links near the top) so that you can quickly scan for the features you are interested in using. when a feature is included, there is a column indicating whether the feature has full support or partial support on each of the 3 DB2 products.

Serge also wrote about the IBM SQL Language Council (SLC) as the group within IBM that reviews all SQL changes and additions to the DB2 family of products. The SLC is made up of representatives from IBM DB2 product development teams and also includes the IBM representatives to the ANSI and ISO database language standards committees. In addition to helping to define and review new SQL for the DB2 products, the SLC is also active in making proposals to enhance the ANSI and ISO standards with features we are interested in adding to the products. The SQL Reference for Cross-Platform development and the "Selected common SQL features for developers of portable DB2 applications" are brought to you by the product representatives of the SLC.

By way of introducing myself to readers of this blog, I am a database language architect at the IBM Toronto Lab and I have been an active member of the SLC for over 20 years. This means that I have quite a long history of working with SQL. I started with the SLC back in 1991 when the Toronto Lab had just delivered Version 1 of DB2 for AIX and the development team was beginning work on what was to become Version 2. This version of DB2 included the introduction of the Starburst compiler technology from the database research team at Almaden Research Center and numerous new features (that we take for granted today) like large object data types, user-defined functions, and user-defined data types. I have been involved with many additions and changes to SQL, participating in a growing the product SQL Reference manual from around 200 pages to what is about 2500 pages today.

I hope that by contributing to this blog I can share some of my experience with others that are interested in learning more about SQL.
Please send me your questions about how SQL works or why it works in the specific ways and I will endeavour to provide answers using this blog.